S
M
T
W
T
F
S
30
90°
64°
31
92°
68°
1
94°
70°
2
95°
69°
3
94°
70°
4
91°
67°
5
85°
63°
6
82°
62°
7
82°
59°
8
79°
57°
9
80°
56°
10
84°
58°
11
82°
55°
12
79°
53°
13
78°
54°
14
80°
53°
15
80°
58°
16
77°
58°
17
78°
57°
18
77°
53°
19
80°
56°
20
81°
57°
21
81°
56°
22
80°
56°
23
81°
55°
24
81°
56°
25
80°
55°
26
78°
54°
27
79°
55°
28
78°
54°
29
79°
53°
30
78°
52°
1
77°
52°
2
77°
51°
3
76°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in New Haven
New Haven's September 2026 forecast shows daily high temperatures ranging from 76° to 95°, with overnight lows between 51° and 70°. The average high for September is 81° with an average low of 57°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in New Haven. See also: October | November | December.
